path: root/Documentation/trace
diff options
authorLinus Torvalds <torvalds@linux-foundation.org>2010-05-18 08:35:04 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2010-05-18 08:35:04 -0700
commit752f114fb83c5839de37a250b4f8257ed5438341 (patch)
treec565c3b6670d21ad7f5cd6cdda5864a76d3f2e0c /Documentation/trace
parentb8ae30ee26d379db436b0b8c8c3ff1b52f69e5d1 (diff)
parentad56b0797e67df5e04b2f1a1e02900145c5c16f2 (diff)
Merge branch 'tracing-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'tracing-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip: tracing: Fix "integer as NULL pointer" warning. tracing: Fix tracepoint.h DECLARE_TRACE() to allow more than one header tracing: Make the documentation clear on trace_event boot option ring-buffer: Wrap open-coded WARN_ONCE tracing: Convert nop macros to static inlines tracing: Fix sleep time function profiling tracing: Show sample std dev in function profiling tracing: Add documentation for trace commands mod, traceon/traceoff ring-buffer: Make benchmark handle missed events ring-buffer: Make non-consuming read less expensive with lots of cpus. tracing: Add graph output support for irqsoff tracer tracing: Have graph flags passed in to ouput functions tracing: Add ftrace events for graph tracer tracing: Dump either the oops's cpu source or all cpus buffers tracing: Fix uninitialized variable of tracing/trace output
Diffstat (limited to 'Documentation/trace')
2 files changed, 50 insertions, 3 deletions
diff --git a/Documentation/trace/events.txt b/Documentation/trace/events.txt
index 02ac6ed38b2..778ddf38b82 100644
--- a/Documentation/trace/events.txt
+++ b/Documentation/trace/events.txt
@@ -90,7 +90,8 @@ In order to facilitate early boot debugging, use boot option:
-The format of this boot option is the same as described in section 2.1.
+event-list is a comma separated list of events. See section 2.1 for event
3. Defining an event-enabled tracepoint
diff --git a/Documentation/trace/ftrace.txt b/Documentation/trace/ftrace.txt
index 03485bfbd79..557c1edecca 100644
--- a/Documentation/trace/ftrace.txt
+++ b/Documentation/trace/ftrace.txt
@@ -155,6 +155,9 @@ of ftrace. Here is a list of some of the key files:
to be traced. Echoing names of functions into this file
will limit the trace to only those functions.
+ This interface also allows for commands to be used. See the
+ "Filter commands" section for more details.
This has an effect opposite to that of
@@ -1337,12 +1340,14 @@ ftrace_dump_on_oops must be set. To set ftrace_dump_on_oops, one
can either use the sysctl function or set it via the proc system
- sysctl kernel.ftrace_dump_on_oops=1
+ sysctl kernel.ftrace_dump_on_oops=n
- echo 1 > /proc/sys/kernel/ftrace_dump_on_oops
+ echo n > /proc/sys/kernel/ftrace_dump_on_oops
+If n = 1, ftrace will dump buffers of all CPUs, if n = 2 ftrace will
+only dump the buffer of the CPU that triggered the oops.
Here's an example of such a dump after a null pointer
dereference in a kernel module:
@@ -1822,6 +1827,47 @@ this special filter via:
echo > set_graph_function
+Filter commands
+A few commands are supported by the set_ftrace_filter interface.
+Trace commands have the following format:
+The following commands are supported:
+- mod
+ This command enables function filtering per module. The
+ parameter defines the module. For example, if only the write*
+ functions in the ext3 module are desired, run:
+ echo 'write*:mod:ext3' > set_ftrace_filter
+ This command interacts with the filter in the same way as
+ filtering based on function names. Thus, adding more functions
+ in a different module is accomplished by appending (>>) to the
+ filter file. Remove specific module functions by prepending
+ '!':
+ echo '!writeback*:mod:ext3' >> set_ftrace_filter
+- traceon/traceoff
+ These commands turn tracing on and off when the specified
+ functions are hit. The parameter determines how many times the
+ tracing system is turned on and off. If unspecified, there is
+ no limit. For example, to disable tracing when a schedule bug
+ is hit the first 5 times, run:
+ echo '__schedule_bug:traceoff:5' > set_ftrace_filter
+ These commands are cumulative whether or not they are appended
+ to set_ftrace_filter. To remove a command, prepend it by '!'
+ and drop the parameter:
+ echo '!__schedule_bug:traceoff' > set_ftrace_filter